Neural And Chemical Control Of Breathing Flashcards
What allows autonomous breathing?
The respiratory pattern generator in the medulla of the brainstem
What sensory information feeds into the respiratory pattern generator?
Partial arterial pressure O2
Partial arterial pressure CO2
pH
Lung stretch receptors
What is mutual inhibition?
Inspiratory pathway can inhibit the expiratory pathway when active and vice versa
Why is the control of inspiration and expiration somatic, while automatic?
Nerves innervate skeletal muscle as opposed to smooth muscle in the autonomic nervous system
What nerves innervate the diaphragm?
What spinal nerve roots are these from?
Phrenic nerves,
C3, C4, C5.
What is Ondine’s curse?
Damage to the respiratory pattern generator following brain trauma or as a congenital defect renders a person forced to breathe manually
Where are the peripheral chemoreceptors found?
Carotid bodies - at bifurcation of the common carotid arteries.
Aortic bodies - located at the aortic arch.
Which nerve innervates the carotid bodies?
Branch of Cranial nerve IX (Glossopharyngeal)
Which nerve innervates aortic bodies?
Branch of cranial nerve X (vagus nerve)
What do the peripheral chemoreceptors primarily sense?
Hypoxaemia (via paO2)
Can also sense paCO2 and pH
What do central chemoreceptors sense?
pH and paCO2
Where are central chemoreceptors found?
Ventral surface of the brain near the medulla, across the blood brain barrier
How do central chemoreceptors sense pH and pCO2 if ions cannot pass through the blood brain barrier freely?
CO2 is able to freely diffuse through - this dissociates into H+ and HCO3- which can then be detected. As there is limited HCO3- buffering capacity, small changes in pH can be detected.
What happens if CO2 remains elevated in the presence of central chemoreceptors?
HCO3- ions will be actively transported through into the choroid plexus to help buffer the pH, which means that the pH required to cause neurone firing will be reset to a lower value.
